The medieval Latin word vagus means literally "Wandering" (the words vagrant, vagabond, and vague come from the same root). It is also called the pneumogastric nerve since it innervates both the lungs and the stomach.

At this location Otto Loewi first proved that nerves secrete substances called neurotransmitters which have effects on receptors in target tissues. Loewi described the substance released by the vagus nerve as vagusstoff, which was later found to be acetylcholine.

Drugs that inhibit the muscarinic cholinergic receptor (anticholinergics) such as atropine and scopolamine are called vagolytic because they inhibit the action of the vagus nerve on the heart, gastrointestinal tract and other organs. Anticholinergic drugs increase heart rate and are used to treat bradycardia (slow heart rate) and asystole, which is when the heart has no electrical activity. Anticholinergic drugs relax the detrusor muscle and cause constipation which again involves the vagus nerve.

Medical treatment involving the vagus nerve

Vagus nerve stimulation (VNS) therapy using a pacemaker-like device implanted in the chest is a treatment used since 1997 to control seizures in epilepsy patients and has recently been approved for treating drug-resistant cases of clinical depression.[1] A convenient, non-invasive VNS device that stimulates an afferent branch of the vagus nerve is also being developed and will soon undergo trials.

A degree of intermittent VNS can be achieved by daily breathing exercises (for example, Pranayama) over a period of several weeks. In some patients, such proactive relaxation exercises have been found to correlate with lower blood pressure and lower heart rate and more stable moods.Template:Fix/category[citation needed] The Valsalva maneuver may activate the vagus nerve and is a "natural" way to achieve the same effect in some patients. Patients with atrial fibrillation, supraventricular tachycardia and other illnesses may be trained to perform the valsalva maneuver (or find it for themselves).

Vagotomy (cutting of the vagus nerve) is a now-obsolete therapy that was performed for peptic ulcer disease. Vagotomy is currently being researched as a less invasive alternative weight loss procedure to gastric bypass surgery[2]. The procedure curbs the feeling of hunger and is sometimes performed in conjunction with putting bands on patients's stomachs, resulting in average weight loss of 43% at six months with diet and exercise[3]. Five pencil-sized scars are the result of the procedure.

See also:

Porphyria This rare disorder can cause seizures and damage to the vagal nerve. Diagnosis, in some cases, may require DNA testing.

Physical and emotional effects

Activation of the vagus nerve typically leads to a reduction in heart rate, blood pressure, or both. This occurs commonly in the setting of gastrointestinal illness such as viral gastroenteritis or acute cholecystitis, or in response to other stimuli, including carotid sinus massage, Valsalva maneuver, or pain from any cause, particularly having blood drawn. When the circulatory changes are great enough, vasovagal syncope results. Relative dehydration tends to amplify these responses.

Excessive activation of the vagal nerve during emotional stress, which is a parasympathetic overcompensation of a strong sympathetic nervous system response associated with stress, can also cause vasovagal syncope because of a sudden drop in blood pressure and heart rate. Vasovagal syncope affects young children and women more often. It can also lead to temporary loss of bladder control under moments of extreme fear.

Research has shown that women who have complete transection of the spinal cord can experience orgasms through the vagus nerve, which can go from the uterus, cervix and probably the vagina to the brain.[2][4]

Effects of vagus nerve lesions

The patient complains of hoarse voice, difficulty in swallowing (dysphagia), pain during swallowing(odynophagia) and choking when drinking fluid. There is also loss of gag reflex. Uvula deviates away from the side of lesion and there is failure of palate elevation.

Additional images

Section of the neck at about the level of the sixth cervical vertebra.

Transverse section of thorax, showing relations of pulmonary artery.

The arch of the aorta, and its branches.

Dura mater and its processes exposed by removing part of the right half of the skull, and the brain.

The tracheobronchial lymph glands.

Section of the medulla oblongata at about the middle of the olive.

Hind- and mid-brains; postero-lateral view.

Upper part of medulla spinalis and hind- and mid-brains; posterior aspect, exposed in situ.

The right sympathetic chain and its connections with the thoracic, abdominal, and pelvic plexuses.

The celiac ganglia with the sympathetic plexuses of the abdominal viscera radiating from the ganglia.

The position and relation of the esophagus in the cervical region and in the posterior mediastinum. Seen from behind.